This invention relates to a method and device for automatically feeding parts having a through-hole to an intended place, and may, for example, be used for feeding projection nuts onto the electrode of a welding machine.
It is known to cause a projection nut being fed in from a parts feeder or the like to abut against a stop surface to be stopped at a predetermined position, and then to advance a feed rod until a guide rod for the feed rod pierces through the threaded hole of the projection nut so as to feed it to an intended place. Such intended place is generally a guide pin for a fixed electrode, which guide pin projects through a positioning through-hole in a steel sheet part set on the fixed electrode. To there is fed the projection nut, whereupon a movable electrode is advanced to weld the projection nut to the steel sheet part.
There is a problem that if misalignment, even very little, is involved in setting the feed rod, the latter can abut against the guide pin for the electrode and be bent. What is considered to be most important is the problem of safety for the operator. If the operator's hand is accidentally nipped between the guide rod and the guide pin, the welding electrode should in no case be allowed to advance. The reason is that if the hand should be nipped in the welding electrode, it will be seriously injured.
The present invention is intended to solve the problems described above.